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