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