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