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