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