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