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