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