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