One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(6,8)(9,10,14,17)(11,15,18,22)(12,13,16,21)(19,20,23,24)(25,26,31,29)(27,34,32,28)(30,37,38,33)(35,36,39,40)(3,7)(6,8)(9,11)(10,15)(12,19)(13,20)(14,18)(16,23)(17,22)(21,24)(26,29)(27,32)(33,37)(35,39) involution — undirected(1,2,5,4)(3,6,7,8)(11,18)(12,16)(13,21)(15,22)(25,27)(26,28)(29,34)(30,35)(31,32)(33,36)(37,40)(38,39)(9,12)(10,13)(11,19)(14,16)(15,20)(17,21)(18,23)(22,24)(25,28,31,34)(26,32,29,27)(30,36,38,40)(33,39,37,35)(1,3)(2,6)(4,8)(5,7)(9,13)(10,16)(11,20)(12,17)(14,21)(15,23)(18,24)(19,22)(25,29,31,26)(27,34,32,28)(30,37,38,33)(35,40,39,36)(1,4,5,2)(3,8,7,6)(9,11)(10,15)(12,19)(13,20)(14,18)(16,23)(17,22)(21,24)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,39)(34,40)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.