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