One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,16,18)(11,12,14,13)(15,23,24,17)(19,21,22,20)(25,26)(27,34)(28,37)(29,33)(30,31)(32,36)(35,39)(38,40)(1,2)(3,5)(4,6)(7,8)(9,11)(10,12)(13,18)(14,16)(15,19)(17,20)(21,23)(22,24)(25,27)(26,32)(28,35)(29,38)(30,34)(31,36)(33,39)(37,40) involution — undirected(1,2,4,6)(3,5,7,8)(9,12,16,13)(10,11,18,14)(15,21,24,20)(17,22,23,19)(25,28,31,29)(26,33,30,37)(27,35,36,38)(32,39,34,40)(3,7)(5,8)(9,13,16,12)(10,11,18,14)(15,21,24,20)(17,19,23,22)(25,27)(26,32)(28,35)(29,38)(30,34)(31,36)(33,39)(37,40)(1,3)(2,5)(4,7)(6,8)(9,14,16,11)(10,13,18,12)(15,22,24,19)(17,21,23,20)(25,29,31,28)(26,33,30,37)(27,35,36,38)(32,40,34,39)(1,2)(3,5)(4,6)(7,8)(9,15)(10,17)(11,19)(12,20)(13,21)(14,22)(16,24)(18,23)(25,30,31,26)(27,34,36,32)(28,33,29,37)(35,39,38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.