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