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)(11,12)(13,15)(14,16)(18,22)(19,20)(25,26,30,27)(28,33,35,31)(29,32,37,34)(36,39,40,38)(1,3)(2,4)(5,8)(6,7)(9,11)(10,14)(12,15)(13,16)(17,18)(19,24)(20,23)(21,22)(26,27)(28,35)(32,34)(36,40) involution — undirected(2,6)(4,7)(10,15)(11,16)(17,19,21,20)(18,23,22,24)(25,27,30,26)(28,33,35,31)(29,32,37,34)(36,38,40,39)(1,3)(2,4)(5,8)(6,7)(9,12,13,14)(10,11,15,16)(17,20,21,19)(18,23,22,24)(25,28)(26,31)(27,33)(29,36)(30,35)(32,38)(34,39)(37,40)(1,4)(2,3)(5,7)(6,8)(9,11)(10,14)(12,15)(13,16)(17,18)(19,24)(20,23)(21,22)(25,29,30,37)(26,32,27,34)(28,36,35,40)(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.