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