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