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