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