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